# A really strange question!?!?!?

ok i know this sounds strange but does anybody know the surface temperature of a 60 watt light bulb?

And please don’t tell me just to put a thermometer onto the glass is there anywhere with specifications? i tried a search on google but couldn’t find anything.

thanks so much if u can help me, it’s really important i know:bow:

Try putting a rectal thermometer up your ass and lick the bulb with your tounge. By using some simple thermo dynamic equations and the laws of conduction, you should be able to calculate the bulbs temperature in this manner. Let me know what you find out cause this has mystified me for years.

genius

This isn’t going to be easy to answer, because no offence but it really is a stupid question! you may as well ask how long is a piece of string?

There are so many diffferent types of lightbulb and they will all vary in surface temp as not only will they use different fillaments but the the outer surface material will also effect the reading…

Cheers
Ace

Unfortunately, this depends on the size of the light bulb, type of bulb and even which way the light bulb is when switched on! In a 60w Halogen bulb, the glass surface temperature can well exceed 500C, :a where as a typical house-hold 60w tungsten lamp base-down will have a surface temperature of 200C or so. If the bulb is base side up, i.e. from the ceiling, then the surface temperature (opposite end to base) may not even exceed 100C as the heat from the filament inside the lamp raises. Also, a lamp in an enclosed casing will be hotter than a lamp in the open. That’s why most enclosed lamp fittings such as outdoor lamps have a 60 watt maximum rating.

Since we determined the question to be stupid (yes it really is :)) because of the lack of data, I want to ask the topicstarter why he wants to know this…

Hmmmmm,

Originally posted by poon
Try putting a rectal thermometer up your ass and lick the bulb with your tounge.

Is this a secret fantasy of yours? ( or something else in that direction!!).

Grtz

How about sticking the bulb up the ass and a thermometer in the piehole?

Does anyone know the temp. of the little tube inside a high pressure sodium bulb ? Or a metal halide? I really need to know!

I know it looks like a stupid question but it is actually a uk regulation that a standard light bulb has to have a surface temp below 90c in order for it to be classed safe when fixed to wood.
So in a project that we have to do in my degree, i need to follow certain regs and prove that my “Model” complies with them.
I therefore then need to know what size light bulb i can put in.

you could experiment - if you are the danger seeking type

waters boiling temp lowers when it isnt pure. mix enough stuff in to verify that it will boil at 90 degrees C. then turn the light bulb on, and submerge it in the water. if the water ever boils, its not safe

A good idea, but already thought of. Plus i don’t think i could justify hiring a team of light bulb testers to test in a real life situation. (it has to be suitable in the real world aswel as in my model)
There has to be specifications somewhere.

If you don’t want to stick a lightbulb or rectal thermometer up the butt you could try this.

Things you’ll need for this project:

1. a hardware store clip-on light (they’re cheap, \$5 at most stores)
2. several different lightbulbs of different shapes and sizes, but all with the same wattage rating
3. a household oven with a window
4. an oven thermometer
5. several hours of free time
Step 1: Setup
Clip the thermometer to the rack in the oven so that the dial is facing out, and you can see it in the window of the oven. Clip the light to the rack, with the reflector facing away from the thermometer, and away from the window. Make sure that the cord doesn’t interfere with the hinges in the oven, because the cord may fray. MAKE SURE THE OVEN IS OFF, AND DOESN’T TURN ON DURING YOUR EXPERIMENT.
We are using the oven because it is intended to get hot inside, and it is also insulated. The oven also will not be heated up by the light from the light bulb, rather it will be heated because of the hot bulb in contact with the air in the oven. This is why it is important to keep the door closed; you want to keep the air you’re heating inside the oven.
The oven thermometer must have a bottom temperature of 100 degrees or lower. The lightbulbs shouldn’t make a temperature rise more than 30-40 degrees. If the temperature inside the oven gets hotter than 140 degrees, be sure to turn the light off and open the oven door to let things cool off. The insulation of the lamp cord will melt, and we don’t want to make an electrical fire accidentally.
Step 2: Taking Data
Plug in the light, and turn it on. Wait with the oven door closed, and make sure the door stays shut the entire time. The temperature should rise. Write down the temperature at 30 minute intervals. At some point, the temperature will stop decreasing. At that time, you can say that the lightbulb is in equilibrium with the oven, meaning that the amount of heat leaving the lightbulb is the same as the amount of heat leaving the oven. This gives you a reasonable measure of the temperature of the lightbulb’s surface. When you’ve reached equilibrium (the temperature stops moving - maybe 1-1.5 hours) you can stop, let things cool back down, and start again with another type of bulb.
Make graphs of the temperature vs. time for the bulbs. Then make a graph of the final temperature vs. bulb type.
Step 4: Results
The wattage listed on the light bulb is a measure of the amount of electrical energy the lightbulb is consuming. The light bulb will change the energy into heat and light. If a lightbulb is producing a lot of heat, then it is not as good as a cooler light bulb. The reason is due to conservation of energy- the electrical energy is converted more into heat that into light for the hotter bulb, and vise versa.
So, I hope this helps.

if it has to be below 90 C, then someone figured out how to measure it efficiently. why not use their method, instead of reinventing the wheel?

//more practical suggestion

if they cant test your model, bullsh*t them ;).

Hmm, ckin2001; are you sure about boiling temp lowers when some stuff (like salts) are disolved in it?

As far as I know (chemistry student), this depends on the nature of the dissolved stuff; salts (most/all?) are less volatile compared to water, so adding some salt to the water will rise the boiling temp. (eg when you add a few grams of ureum to 1litre of pure water, the boiling point will rise to about 105Â°C)

You could add liquids with a lower boiling point (eg Ethanol). Ethanol and water form a true mix (unlike many other organic liquids and water that form two layers). This mix should have a lower boiling point. (BP Ethanol: about 77Â°C?)

If you need 60 watts of light, but don’t mind the bulb being a little over sized, then a 12 Watt CFL (Compact Fluorescent Lamp) should do the trick. These give the same light as a 60 watt light bulb, but will not get hot to the point where one cannot touch the bulb. Some of the newer ones like philips are shapped to look like a regular light bulb, although a little larger than a typical 60w bulb.

turn on the light buld and wait until it is hot.

when it is hot, let some drops of water fall on the bulb’s surface. if it evaporates immediately or at least after a few seconds, the bulb is hotter than 90^C.

PS:
i also recommend a CFL. so you don’t need to worry about the temperature.

Originally posted by a minor threat
[B]turn on the light buld and wait until it is hot.

when it is hot, let some drops of water fall on the bulb’s surface. if it evaporates immediately or at least after a few seconds, the bulb is hotter than 90^C.

PS:
i also recommend a CFL. so you don’t need to worry about the temperature. [/B]

And if you got bad luck, the bulb will explode and glass will be flying around…

Pretty stupid, as this can hurt you serious!

of course you should not submerge the hot glass in icy water.

i am talking of one or two drops.

this method seems to me less dangerous than licking it.

instead of waterdrops you can wet your fingers, shake the water off. after that you can spray very few water onto the bulb, so the risk of explosion should be reduced to zero and you can still hear to water turn to steam (if so).

Originally posted by a minor threat
[B]of course you should not submerge the hot glass in icy water.

i am talking of one or two drops.

this method seems to me less dangerous than licking it.

instead of waterdrops you can wet your fingers, shake the water off. after that you can spray very few water onto the bulb, so the risk of explosion should be reduced to zero and you can still hear to water turn to steam (if so). [/B]

Ok, try this (at your own risc) and post the results here